Endothelial samplingin situenables genetic characterization of vein of Galen Malformation

Background and Objectives Vein of Galen malformation (VOGM), the result of arteriovenous shunting between choroidal and/or subependymal arteries and the embryologic prosencephalic vein, is among the most severe cerebrovascular disorders of childhood. While endovascular treatment options have improved outcomes, morbidity and mortality remain high. We hypothesized that in situ analysis of the VOGM lesion using endoluminal tissue sampling (ETS) is feasible and may identify somatic mutations and transcriptional aberrations. A mechanistic understanding of VOGM genetics, pathogenesis, and maintenance will guide future therapeutic efforts. Methods We utilized a Mendelian, trio-based study design, collecting germline DNA (cheek swab) from patients and their families for whole exome sequencing (WES). In situ VOGM ‘endothelial’ cells (EC), defined as CD31+ and CD45-, were obtained from coils via ETS during routine endovascular treatment. Autologous peripheral femoral ECs were also collected from the access sheath. Single-cell RNA sequencing (scRNA-seq) of both VOGM and femoral ECs was performed to demonstrate feasibility to define the transcriptional architecture. Comparison was also made to a published normative cerebrovascular transcriptome atlas. A subset of VOGM ECs was reserved for future DNA sequencing to assess for somatic and second-hit mutations. Results Our cohort contains 6 patients who underwent 10 ETS procedures from arterial and/or venous access during routine VOGM treatment (aged 12 days to ∼6 years). No periprocedural complications attributable to ETS occurred. Six unique coil types were used. ETS captured 98 ± 88 (mean ± SD; range 17-256) experimental ‘endothelial’ cells (CD31+ and CD45-). There was no discernable correlation between cell yield and coil type or route of access. Single cell RNA sequencing demonstrated hierarchical clustering and unique cell populations within the VOGM EC compartment compared to autologous femoral controls when annotated using a publicly available cerebrovascular cell atlas. Conclusion We report the first successful utilization of ETS for VOGM. ETS appears safe and may supplement investigations aimed at development of a molecular-genetic taxonomic classification scheme for VOGM. Moreover, results may eventually inform the selection of personalized pharmacologic or genetic therapies for VOGM and cerebrovascular disorders more broadly.